1. Field of the Present Invention
The present invention relates to an apparatus for measuring transmissivity, and more particularly, to a relatively simple apparatus for measuring transmissivity, which can measure the transmissivity of a patterned glass substrate.
2. Description of Related Art
Recently, in response to shortages of energy and resources and environmental pollution, the development of high-efficiency photovoltaic modules is underway on a large scale. For photovoltaic modules, the transmissivity of a cover substrate, e.g., a glass substrate, has an effect on the efficiency of photovoltaic modules. Accordingly, massive research and development is underway in order to increase transmissivity, for example, by minimizing internal absorption using a glass substrate composition or by improving transmissivity using a coating. In addition, two-dimensional (2D) array patterning is also performed to form a pattern in the surface of a glass substrate on which light is incident in order to increase the transmissivity of the glass substrate.
At present, patterned glass substrates are widely used not only for photovoltaic modules, but also for flat panel displays (PDPs). Glass substrate manufacturers precisely examine, in real time, the transmissivity of patterned glass substrates, which are continuously produced, by radiating light onto the patterned glass substrates in the process of manufacturing the patterned glass substrates.
As a device for measuring the transmissivity of patterned glass substrates, a spectrometer is used in the related art. However, ISO 9050 International Standard regulates that the transmissivity of a glass substrate by solar light be calculated by multiplying wavelength-dependent transmissivity with the wavelength-dependent sensitivity weight factor of a measuring standard light source D65 and a measuring device. Accordingly, the spectrometer of the related art is configured such that it exhibits wavelength-dependent transmissivity by receiving all visible wavelengths of light ranging from 380 nm to 780 nm and then processing them. That is, in order to measure the transmissivity of a glass substrate using the spectrometer of the related art, all of the wavelength-dependent transmissivities of the glass substrate of interest must be measured.
FIG. 1 is an example view depicting the process by which incident light is received by a spectrometer, in which the transmissivity of a patterned glass substrate of the related art is measured, and FIG. 2 is view depicting laser beam profiles on a patterned glass substrate and a glass substrate without a pattern after the laser beam has passed through the glass substrates. Here, reference numeral “20” is an integrating sphere, and “21” is a detector that receives light. FIG. 2 (a) shows the laser beam profile, which is diffused after the laser beam has passed through the patterned glass substrate, and FIG. 2 (b) shows the laser beam profile, which is diffused after the laser beam has passed through the glass substrate without a pattern.
As shown in FIG. 1, the spectrometer of the related art fails to precisely measure the transmissivity of the patterned glass substrate because the incident light is greatly diffused after having passed through the patterned glass substrate. This is because the detector 21 of the integrating sphere 20 may fail to receive light if the incident light is greatly diffused after having passed through the patterned glass substrate, as can be seen from FIG. 2 (a). Accordingly, there is a problem in that, when the transmissivity of the patterned glass substrate is measured using the spectrometer of the related art, the result is unreliable. There is another problem in that the transmissivity of the patterned glass substrate is underestimated.
The information disclosed in this Background of the present invention section is only for the enhancement of understanding of the background of the present invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.